#include<stdio.h>
#include<unistd.h>
#include<stdlib.h>

int g_val=100;
int main()
{
  pid_t id=fork();
  if(id==0)
  {
    int cnt=0;//子进程
    while(1)
    {
      printf("child,pid:%d,ppid:%d,g_val:%d,&g_val:%p\n",getpid(),getppid(),g_val,&g_val);
      sleep(2);
      cnt++;
      if(cnt==5)
      {
        g_val=50;
        printf("child change g_val: 100->50");
      }
    }
  }
  else
  {
    //父进程
    while(1)
    {
      printf("father,pid:%d,ppid:%d,g_val:%d,&g_val:%p\n",getpid(),getppid(),g_val,&g_val);
      sleep(2);
    }

  }

  return 0;
}
